1. Field of the Invention
The present invention pertains to an ophthalmic lens that allows for post-fabrication correction of higher order aberrations or spherical corrections. More in particular, the invention can be used in IOLs and contact lenses wherein lens components respond to an external energy source, such as a laser, to allow adaptive structures in an interior lens phase to be altered in dimension to thereby adjust or flex the lens shape in a manner akin to methods used in the field of adaptive optics (AO) in astronomical telescopes for higher order wavefront corrections.
2. Description of the Related Art
Post-fabrication adjustment of optical characteristics of lenses is needed in various ophthalmic lens types. In one case, cataract patients would benefit from post-implant power adjustability of an IOL implant. In another case, posterior chamber phakic IOLs could benefit from post-implant power adjustability since biometry cannot insure proper power selection. Also, contact lenses would benefit from post-fabrication curvature adjustment to limit the number of lenses that needed to be maintained in inventories.
Cataracts are major cause of blindness in the world and the most prevalent ocular disease. Visual disability from cataracts accounts for more than 8 million physician office visits per year. When the disability from cataracts affects or alters an individual's activities of daily living, surgical lens removal with intraocular lens implantation is the preferred method of treating the functional limitations. In the United States, about 2.5 million cataract surgical procedures are performed annually, making it the most common surgery for Americans over the age of 65. About 97 percent of cataract surgery patients receive intraocular lens implants, with the annual costs for cataract surgery and associated care in the United States being upwards of $4 billion.
A cataract is any opacity of a patient's lens, whether it is a localized opacity or a diffuse general loss of transparency. To be clinically significant, however, the cataract must cause a significant reduction in visual acuity or a functional impairment. A cataract occurs as a result of aging or secondary to hereditary factors, trauma, inflammation, metabolic or nutritional disorders, or radiation. Age-related cataract conditions are the most common.
In treating a cataract, the surgeon removes material form the lens capsule and replaces it with an intraocular lens (IOL) implant. The typical IOL provides a selected focal length that allows the patient to have fairly good distance vision. Since the lens can no longer accommodate, the patient typically needs prescription eyeglasses for reading.
The surgeon selects the power of the IOL based on analysis of biometry of the patient's eye prior to the surgery. In a significant number or cases, after the patient's eye has healed from the cataract surgery, there is a refractive error was beyond the margin of error in the biometric systems. Thus, there remain intractable problems in calculating the proper power of an IOL for any particular patient. To solve any unpredicted refractive errors following IOL implantation, the ophthalmologist can perform a repeat surgery to replace the IOL—or the patient can live with the refractive error and may require prescription eyeglasses to correct for both near and distant vision.
What is needed is a lens system that provides means for post-fabrication or post-implant adjustment of optical characteristics and dioptic power. What also is needed is a lens system that can correct higher order aberrations.